Electrical relay



y 944. A. H. LAMB 2,353,616

ELECTRICAL RELAY Filed Dec. 4, 1942 Patented Julyll, l944 EIECTRICAL RELAY Anthony 1!. Lamb, Hillside, N. J., asslgnor to Weston Electrical Instrument Corporation, Newark, N. 1., a corporation of New Jersey Application December 4, 1942, Serial No. 467,893

9 Claims. (Cl. zoo-110) This invention relates to electrical relays and particularly to sensitive electrical relays of the instrument type that develop only relatively small forces for effecting the engagement of the contact arm with the relatively stationary contact or contacts.

The conventional instrument type relay has a permanent magnet field system including a cylindrical core coaxial with and spaced from the cylindrical surfaces of the outer member, which an auxiliary member angularly adjustable on the core to concentrate the iiux at the region in which the coil moves as the contact arm approaches a relatively stationary contact. An object is to provide a relay of the instrument type in which the magnetic field system includes an auxiliary member connected to and adjustable with a relatively stationary contact of the relay, the auxiliary member being so positioned as to effect a usually is the magnetized member of the field I system, to provide an air gap of constant width flux concentration at the region occupied by the moving coil as the movable contact arm nears the stationary contact.

in which the moving coil is supported for angular movement. The magnetic flux is evenly distributed along the air gap and the angular displacement of the coil per unit change in current flow is constant over the full range of coil movement. Conversely, a given increment in current flow above the value that effects an incipient contact closure develops only a slightly increased torque for pressing the contacts into engagement, and this torque increase has been the same for all adjustments of the stationary contact along the scale range of the instrument type relay. It has been proposed to shape the opposed surfaces of the air gaps to obtain a progressive variation of the flux density along the air gap or a flux concentration at a particular region of the air gap, and these designs provide a relatively high torque lncrement,- for a unit increase in current flow, when the moving coil is in the region of high flux density. These constructions are quite expensive and they are not suitable for relays in which the "stationary contact or contacts are adjustable along the range scale to obtain contact closures at any desired angular positions of the recreased torque, and thereby increases the contact pressure and ailords reliable contact closures.

An object of this invention is to provide an instrument type relay having a magnetic field system that includes an auxiliary member ad- .iustable to increase the iiux density at a selected region along the path of angular displacement oi the moving coil system of the relay. An objectis to provide a sensitive relay including a permanent magnet with spaced polar surfaces at opposite sides ofa-core or soft iron or the like, and

These and other objects and advantages of the invention will be apparent from the following specification when taken with the accompanying drawing in which:

Fig, 1 is a fragmentary plan view .of an embodiment of the invention in a relay oi the per manent magnet-iron core type;

Fig. 2 is a perspective view of the adjustable, but relatively stationary, contact member and core system of the relay Fig. 3 is a somewhat diagrammatic perspective view of the contact members and.core system of the relay; and

Fig. 4 is a perspective view of another form of core system and associated relatively stationary contact arm.

In the drawing, the reference numeral l' identitles the coil element of an instrument type relay, the coil being pivotally supported for angular movement in the arcuate gaps between the soft iron core 2, and the opposed polar surfaces of a permanent magnet 3. in the usual manner upon a supporting plate or base member 4 that is hired with respect to the permanent magnet. The coil i carries a pointer or contact arm I that moves along a scale plate 6 and has a contact 1 for cooperation with a contact 8 on a relatively stationary contact arm 8 that is supported on, and preferably angularly adjustable with respect to, the core 2.

The auxiliary member ID of magnetic material is secured to the contact arm 9, and both are mounted on the core 2,'by a screw II, for angular adjustment about the axis oi the coil I. The auxiliary member In is a narrow bar of soft iron that is normal to the contact arm 8 when, as illustrated, the contact arm I of the moving sysstem is normal to the median plane of the coil 2. The auxiliary magnetic member I0 is therefore positioned to produce a concentration of the magnetic flux at the region in which the coil i moves as the contact arm I approaches the relativeb stationary contact arm I. The auxiliary The core is mounted member l may be a small bar magnet but, in general, it is satisfactory and economical to form the member. I. of soft iron.

The contact arm 9 may be adjusted to locate the stationary contact 8 at any desired position along the scale I but, since the auxiliary member i0 is secured to the contact arm 5, the moving coil I will always be in the region of flux concentration when the relay contact points are closely adjacent each other. The concentration of the magnetic flux at the region of contact closure causes the coil i to rotate an increased amount,

for a given current increment, thereby applying more pressure to the engaged contact and establishing a better contact closure.

As shown in Fig. 4, the auxiliary core member l0 may be an iron strap of inverted U-shape when the air gaps are of sufficient width to accommodate this increased core width. The method of operation of this embodiment will be apparent from the above discussion of the effects of the bar auxiliary element of Figs. 1 to 3 inclusive.

The illustrated relay conforms to conventional practice in that the opposed polar surfaces of the magnet 3 are coaxial with the surface of a core 2 that has the form of a right circular cylinder. It is tobe understood that the polar surfaces may be eccentric to the core 2 to obtain a variation of the flux concentration along the gaps but, regardless of any progressive variation in flux concentration, the auxiliary core device ID will result in a flux concentration in the contact-closure region. Furthermore, the invention may be incorporated in relays in which the magnetic field system takes the form of a magnetized core within a yoke or outer member of soft iron. It is therefore to be understood that the invention is not limited to the particular constructions herein described and illustrated, and that many variations that may occur to those familiar with the design of sensitive electrical relays fall within the spirit of my invention as set forth in the following claims.

I claim:

1. A relay of the instrument type including a magnetic system comprising a core member of magnetic material and an outer member of magnetic material with surfaces spaced from opposite sides of said core member to provide arcuate gaps, the opposed surfaces of said core member and said outer member being substantially coaxial cylindrical surfaces, a coil supported for angular movement in said gaps, and a contact arm carried by said coil for cooperation with a relatively stationary contact, said relatively stationary contact being manually adjustable along the path of said contact arm; characterized by the fact that said magnetic system includes means for establishing a non-uniform and relatively fixed flux field at the arcuate gaps, said means comprising an auxiliary member of magnetic material angularly adjustable on said core member, and means for securing said auxiliary member to said core member in a desired relatively fixed position in radial alinement with the gap region occupied by the coil at a closure of said contact arm on said relatively stationary contact.

2. A relay as recited in claim 1, wherein said surfaces of the outer member of magnetic material are uniformly spaced from said core member, thereby tending to establish a constant flux density along the arcuate gaps.

3. A relay as recited in claim 1, wherein said core member is soft iron, and said outer member is a permanent magnet.

4. A relay as recited in claim 1, wherein said core member is soft iron, said outer member is a permanent magnet, and said auxiliary member is of soft iron.

5. In an instrument relay, a magnetic field system comprising a cylindrical core member and an outer member having cylindrical surfaces 00-. axial with said core member and spaced therefrom to provide arcuate gaps at opposite sides of said core member, one of said members being a permanent magnet, a coil angularly movable in said arcuate gaps, a contact arm carried by said coil, and a cooperating contact arm supported on said core member for anuglar adjust-.

ment about the axis of said coil.

6. In an instrument relay, a magnetic field system comprising a cylindrical core member and an outer member having cylindrical surfaces coaxial with said core member and spaced therefrom to provide arcuate gaps at opposite sides of said core member, one of said members being magnetized, a coil angularly movable in said arcuate gaps, a contact arm carried by said coil, a cooperating contact arm supported .on said core for angular adjustment about the axis of said core member, and an auxiliary member of magnetic material on said core member and connected to said second contact arm for angular adjustment thereby; said auxiliary member being angularly positioned, with respect to said second contact arm, to increase the magnetic fiux density in the regions of the arcuate gaps in which the coil is located at closure of the relay contact arms.

7. In an instrument type relay, the combination with a permanent magnet having spaced polar surfaces. a core between and spaced from said polar surfaces by air gaps, a moving system comprising a coil pivotally supported in said air gaps and a contact arm carried by said coil, a relatively stationary contact for cooperation with said contact arm, and means supporting said contact for angular adjustment about the axis of said coil, of an auxiliary magnetic member for increasing the flux density inat least one gap at the region occupied by said coil at engagement of the contact arm with said relatively stationary contact, said auxiliary magnetic member being connected to and movable with said contact.

8. In an instrument type relay, the invention as defined in claim I, wherein said auxiliary magnetic member is a bar of soft iron angularly adjustable on said core.

9. In an instrument type relay, the invention as defined in claim '7, wherein said core is a right circular cylinder and said auxiliary magnetic member comprises a U-shaped strap of soft iron angularly adjustable on said core.

ANTHONY H. LAMB. 

